Method of distributing motive fluid in compound engines



(No Model.) 2 sheets- -Shet' 1.v

H. H. WESTINGHOUSE & P. M. RITES. METHOD OF DISTRIBUTING MOTIVE. FLUID IN COMPOUND ENGINES. 7

No. 895,935. Patented Jam-8, 1889.

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(N ModeL) 2 Sheets-Sheet 2.]

I H. H. WESTINGHOUSE & F. M. RITES. v METHOD OF DISTRIBUTING MOTIVE FLUID IN COMPOUND ENGINES.

No. 395,935. Patented Jan. 8, I889.

' WITNESSES: INVENTORS N. PETERS. plvolaillhognpher. \Vashmglom u. c.

U ITED PATENT Fries.

HENRY HERMAN \YESTINGIIO'USE AND FRANCIS M. RITES, OF PITTSBURG, PENNSYLVANIA.

METHOD OF DISTRIBUTING MOTlI/E FLUID IN COMPOUND ENGINES.

SPECIFICATION forming part of Letters Patent No. 395,935, dated January 8, 1889.

Application filed S t mber 19, 1888. Serial No. 285,801. (No model.)

To all whom may concern:

Be it known that we, HENRY HERMAN VEST- INGHOUSE and FRANCIS M. RITEs, citizens of the United States, residing at Pittsburg, in

the county of Allegheny and State of Pennsylvania, have invented or discovered certain new and useful Improvements in the Method of Distributing Motive Fluid in Compound Engines, of which improvements the following is a specification.-

The object of our invention is to effect the utilization of the expansive force of steam or other elastic fluids, when applied in engines of the compound type, more completely and '15 perfectly than has heretofore been practicable, by the avoidance of an. intermediate reduction of pressure and a loss of motive fluid in filling clearancespaccs, unaccompanied in either case by the performance of useful work,

both of which objections obtain to a greater or less degree in prior constructions.

To this end ourinvention, generally stated, consists in a novel method of effecting the disl'ril'vution functions of a compound (mgine by supplying motive fluid throughout a portion of thc'stroke of the piston to a preliminary or high-pressure cylinder and a continuously-communicating clearancespace expanding such motive fluid in said cylinder and clearance-space throughout the remaining portion of the stroke, exhausting the motive fluid directly into a secondary orlowpressure cylinder, expanding the motive fluid between the primary and secondarycylinders 3 5 througluimt a portion of the stroke of the piston of the latter, terminating the stroke of. said piston under simple expansion and coincidently compressing motive fluid in the preliminary cylinder and clearance-space to ini- 40 tial pressure, and, final] y, exhausting the motive fluid from the secondary cylinder.

The improvements claimed are hereinafter fully set forth.

To completely attain the recognized economic advantage of cylinder compression, it is necessary that the same shall be finally raised to the degree of initial pressure, or that exerted upon the piston at the commencement of the stroke, and there being in the operation of a compound engine in practical service frequent variations in pressure or load, orboth, the attainment of the advantage above referred to is further necessarily dependent upon the correspondence of terminal compression with initial pressure at each of the different grades of expansion or initial motive-fluid pressure under which the engine may from time to time be operated. Such maintenance of correspondence of terminal compression with initial pressure independent of vz'iriations of load or motive-fluid supply pressure, which we do not know or believe to have been effected prior to our invention we attain by preventing variations of the point of initial compression from inducing variations in the degree of terminal compression through the induction of corresponding variations in pressure at the point of initial compression.

The distiu guishin g feature of our invention is the coincident etfection of low-pressure expansion and high-pressure compression within a space of determined volume and the maintenance of high-pressure terminal compression uniformly at initial pressure independently of variations of load or pressure by corr(- s1' onding variations in. the grade of expansion, the variations of pressure at the point of highpressure compression compensating the variations of the point of highpressure compression, and terminal high- So pressure compression being thereby caused to be equal to initial pressure at all grades of expansion in operation. The high-pressure compression curves produced in indicator diagrams will necessarily vary with variations of initial pressure; but their terminal in the several variations will coincide in each case with the initial pressure.

The practical application of our method of distributing motive fluidthat is to say, of performing the several functions involved in the exertion of its expansive action upon the pistons of a compound engine is exemplified in the operation of the engines set forth in an application for Letters Patent filed by us ,under date of March 17, 1888, Serial No.

267,519, and will be herein explained by reference to an engine illustrated in the drawings, which, while differing in minor structural features from those of said application,

aceords therewith inthe embodiment of the mechanical elements requisite t'orthe employment of our method.

in the accompanying drawings, Figure l is a vertical longitudinal central section through a eompound engine adapted to the practice oi? our invention; and Fig. 2, an end view, in elevation, of the same, as seen from the right.

The drawings illustrate a single-acting eompound engine of the *estinghousc type having a preliminary or high-pressure \"lll'l(l(f1',' I1. and a secondary or low-pressure cylinder, 2. which are secured side by side to the top oi a closed erz'ink-ease. 5,etn1stitut-ing the bed or support of the engine, and serving also as a tanl: or receptacle for the lubricating material ot the journals and erank-pins of the erank-shatt 4-. the journals 5t) of \vhieh rotate in bearings l-l, tixed in the ei'n'lsot' the crankease 5. The evlinders l and are fitted, 1e speetively. with pistons T and R, which are eoupled by eonneeting-rods t) to the crankpins ot' double-cranks ltl, set oppositely or with their pins one hundred and eighty degrees apart on the erank-shatt t.

Motive fluid is admitted to the high-pressnre eylinder l, exhausted therefrom to the hnv-pressure cylinder 2, and thence exhausted into the atmosphere or into a condenser by a single distributionwalve which reeiprocatcs in a valve-chest, fl, n'ovided with nozzles or passages and l l, to whieh a supply and an exhaust pipe are respeet ively eonneeted and communieating with the high and the low pressure cylinders by ports 12 and 1 The val vc-ehest is prel'er: ll ily l i ned with a bushing, to, communieating by proper series of ports with the supply and exhaust passages 15 and ll and the e vlinderports 'liand '14-. The distribut ion-val\e. \vhieh in this instanee is of the piston type, is eomposed ot' a high-press ure section, its, and a low-pressureseetimi,13ft, which are seenred upon and reeiproeate eoineidently with a valve-stem, 'llhz'u-t-uated by an eeeentrie, it), which is mounted l'reely upon the erank-shat't fl, and is varied and adjusted in position relatively to the erank-line, so as to el'leet variation of the degree ol expansion in aeeordanee with variations ol pressure or load, or both, by an automatic eut-ot't governor ol'an suitable and preferred construction. The governor illustrated, which is mounted upon a supporting-wheel, 22, fixed upon the erank-shat't l-, is adapted, through pivoted weight-arms and springs, to et'feet: the movement ol the adjust able eeeent rie 2O transversely to the crank-line,and thereby to vary the grade of expansion or point olf cut-oft, as above stated. The valve-stem l t) iseonneeted to one arm of a bellwranlt' lever, 15, pivoted in bearings on the cap-plate of the cylinders, the other arm of said lever being coupled to an eeeentric-rod, 1!), which is connected to the strap 21. ot' the eccentric 20. in the engine of similar type. illustrated in our application, Serial o. 437,519, before reterrcd to, the bell crank lever 4:13 W153 eou jiled directly to the eccentric-strap by the eccentric-rod it), this construction involving a minimum angularity of said rod; and eonsequentl y minimum disturbance olf lead due to such angularity, in order that the variation oi. the grade of expansion should be equal, as nearly as may be, in the two cylinders, sueh equality being desirable for the attainment of the best result with the employment of saturatetl steam and within the practicable range of regulation by the governor. in the present instance a eonstruction is shown under which the action ot a substal'itially greater angularity of the eecentrie-rod is exerted upon the distrilnltionvalve, the eeeentrie-strap 21 having a short upwardlyprojeet'i11 arm, which is coupled by a pin, 2a, to a sliding bar, 27, titted to reciprocate in guides 2s, seen red. to the crank-ease, and coupled l.1ypin,2l,to the eccentric-rod it).

It will. be seen that the etlfeet ot? the angularity of the eeeent-ric-rot'l. upon the valve at late grz'ules otf expansion or points of cut ofl, the valve being setsqnare for a detcnrmined intermediate point, is materially greater than in the engine oi application, Serial No. 267,519, and that therefore there will be in such cases an increase of lead on the high-pressure port at the expense otT an equal decrease on the low-pressure port, by which a longer cut olt' will be elt'ected in the high-pressure than in the low-pressure cylinder, in order to enable eom n'ession in the high-pressure cylinder to be raised to a higher (lGglQO than that which would be resultant upon an equal point of cut off in both cylinders. ()11 the other hand, the relatively decreased angularity of the eccentric-rotil. at early points of cut oil? induces an increase of lead on the low-pressure port and a deerease on the high-pressure port, and eonsetpiently a relatively longer en t oil in the low-pressure than in the high-pressl'lre eylinder. This provision for a relative variation of the points of cut oft in the two cylinders is made in order torender the engine adapte able to operation with n'iotive tluids having the eharaeteristies ot' pert'eet gases, or those not containing condensible elements within the range of working pressu res, as su 'ierheated steam or compressed air, with 'wh ieh the curve of eompound expansion, not being influenced by coi'u'lensation and re-evaporation, differs from that induced in the employment of superheated steam.

The distance between the sections 38 and 1-30 of the distribution-valve and their relation in position and degree of traverse to the port 12 of the high-pressure cylinder are so fixed that the space within the val vc-eht'sst; bushing 4-0, between the sections 38 and 39, together with that within the port 12, shall constitute a clearance space or chamber, l), which is continuously in comnninication. with the hi ghpressure cylinder. o have found in practice that with the employment of saturated steam and within the ordinary range of variation ol expansion the most perfect results have been obtain ed by the use of a clearancechamber the capacity of which bears substantially the same ratio to the volume of the high-pressure cylinder as that of the latter to the volume of the low-pressure cylinder; but it will be obvious that the capacity of the clearance-chamber may, under the conditions last recited, be increased or diminished with a corresponding variation from maximum useful effect.

The duty of the valve-section 39 is to open and close the port or series of ports in the valve-bushing 40 communicating with the supply-passage 15, thereby performing the functions of admission and cut off for the high-pressure cylinder, the cut off being effected at dilt'erent points in the stroke of the piston, respectively, in accordance with the, variations of position of the eccentric 20 by the governor. The travel of the valve is such that the high-pressure port 12 is continuously open, and h enee the exhaust and compression of the high-pressure cylinder are effected independently of the valve-section 38, the duty of which, other than as a boundary of the clearance-space AB, is limited to the functions first above stated. The valve-section 39 effects the opening and closure of the low-pressure port 1%, and thereby performs the functions of admission, cut off, exhaust, and compression for the low-pressure cylinder, and also those of exhaust for the high-pressure cylinder during the period of the stroke in which the lmv-pressure port it is open and the valve-bushing ports of the supplypassage 15 are closed, and of compression for the high-pressure cylinder during the period in which both' the low-pressure port ]-t and the valve-bushing ports of the supplypassage 15 are closed. In each case, moreover, the valve. -seetion Ell) acts as an end bonmlary ot the elearan(e-space 42.

In operation motive fluid supplied from the passage 15 to the clearance-cl\amber and the space above the piston 7 of the preliminary or high-pressure cylinder 1 effects the downward movement of said piston at substantially initial pressure throughout the preliminary portion of its stroke at a point in which, regulated by the governor under existing conditions of load and pressure, the 'alve-sec-tion 39 closes the ports communicating with the passage 15 and cuts ot't' the supply of motive. fluid, the remainderoi' the stroke of the highpressure piston being effected by the expansion of the motive fluid previously admitted and remaining in the clearance-chainber and high-pressure cylinder. In the further traverse of the valve the valve-section 31') opens the low-pressure port it and admits the moti ve fluid contained in the clearance-chamber and high-pressu re cylinder to the low-pressure cylinder, which motive fluid effects the preliminary portion of the stroke of the low-pressure piston 8 under compound expansion exerted between the smaller and larger cylinders. The distrituition-valve has meanwhile commenced its traverse in the opposite direction, in the course of which, at'a point regulated by the governor, its section 39 closes the low-pressure port 14-, cutting off the supply of motive fluid from the low-pressure cylinder and coincidently closing the clearance-chamber 42, and thereby commencing high-pressure compression. The remaining portion of the stroke of the low-pressure piston is effected under simple expansionthat is to say, by the expansion of the motive fluid inclosed in the low-pressure cylinder, the motive fluid inclosed in the high-pressure cylinder and clearanee-chamber bein meanwhile, in and by the upward stroke of the highpressure piston, compressed at its terminal to substantially initial pressure. Further movement of the valve in the same direction effects the exhaust of the motive fluid which has impelled the low-pressure piston, and admits motive fluid to the clcarance-ehamber and highn-essure cylinder for the next succeeding stroke of the piston oi the latter, such new supply being subject to no reduction of pressure in filling the elcaranee-chamber, as it meets therein a previous supply of equal pressure, which is utilized in the exertion of such pressure upon the high-pressure piston in the stroke about to be made.

Variations of the grade of expansion in the operation of the engine would under previous practice involve different degrees, respectively, of terminal high-pressure compression, from the fact that greater or less volumes of motive fluid are, proportionately to the lateness or earliness of the cut off, admitted to the high-pressure cylinder, while the compressive action of the piston, being exerted through the same space in each case, is uniform at all points of cut off. In the practice of our invention we counteract and compensate for such tendency to variation of the de gree of terminal compression above or below initial pressure by e'ltecting each and every grade of low-pressure expansion coincidently with the initiation of high-pressure compression within a clearance-space of' such volume as has been determined by experimental research to be requisite to admit of the degree of terminalcompression being raised to without exceei'ling that of initial pressure at the commencement of the stroke. Each change of the point of cut off is consequentlyaccompanied by a corresponding change of pressure at the pointof initial compression, (which point corresponds with the point of cut off,) due to the greater or less amount of motive fluid which has been expanded from the liighn'essnre CYlilltlOl into the low-pressure cylinder, so that the later the cut oil and the less the volume of motive fluid on which compression is to be exerted the greater will be the pressure of said volume, and, conversely,

the earlier the cut oflj' and the greater the volume of motive fluid to be compressed the less will be its pressure.

It will be seen that the practice of our invention involves a substantial departure from that win ch has heretofore generally prevailed, to Wit: reducing clearance to the least measure practicable. lVe have discovered, and denumstrated by experiment as the basis of our present invention, that such reduction otf clearance is unnecessary to the successful and eeonomimd utilization of the expansive force of motive liuids, and, l'11rtl1er,that a material advantage is attained by an increase of clearance much beyond the degree heretofore deemed desirable or even admissible \vhen employed asan agent in effecting ctmipression to initial \vorking pressure, such advantage being by our invention rendered ctmtiuuously available, under the conditions existing in ordinary service, by a distribution of motive ttuid which maintains the correspondeuce of terminal compression and initial pressure without disturbance from the variations of pressure and load, which are uorn'tally encountered and provided for in the operation of the standard constructions known and ap proved in preseu t, st eam-eugineering pntct'ice.

The engine herein described and shown is not claimed as of our present invention, being introduced only to facilitate the description thereotlrv ret'ru-e1ureto a mechanism suitably adapted to its application, and according, moreover, in its essential elements with that set forth in our application, Serial No. 207,512, hereinbet'ore referred to.

\Ve claim as our invention and desire to secure by Letters Patent?- 1. The improvement in the method of disdributing motive fluid in compound engines, which consists in supplying the same to a preliminary or high-pressure cylinder and a eonti1inously-commu n icatingclearan ee-ehamber of determined volume, substantiz'tlly greater than that required to serve as an a\'e nue for the passage ol moi ive fluid, exhaust ing the same under comprmnd expansion into at secondary or low-pressure eyliluler, and there-1ft erelosing the exit from said clearance chamber and raising high-pressure comliu'ession to initial pressure therein, substantially as set forth.

2. The improvement in the method of distributing motive fluid in compound engines, which consists in raising higl1-] )1.'essu.re compression to initial pressure in a chamber oti' suitable determined volume without limitation by or disturbance from variations of load or initial pressure by commencing highpressure compression eoineidently with lowpressure expansiomsul)stantially as set forth.

2;. The improvement in the methoi'l of distributing motive tluid in compound engines, which consists in supplying the same to a preliminary or high-pressure cylinder and a cont in111n1slyc1nnm 11 nieati ngclearance-cl1amber of suitable determined volume, exhaustiing the same under compound expansion into a secondary or low-pressure cylinder, varying the grade of simpleexpansion in the same direction in both the high and the low-pressure cylinders, and etleeting high-pressure compressimi to initial pressure in the clearancechamber by initiating said compressimi coineidently with each and every variation of the grade of low-pressure expansion, substantially as set forth.

-.I-. The improvmnent in the method of distributing motive fluid in compound engines, which consists in counteracting and compensating for the tendency of variations of the point; of cut ot't' to induce variations in terminal high-pressure compression by ti ti eeting a corresponding vz'u-ir'ition of? pressure at the point of initial mmtpression coincidei'itly With each variation of the point oi cut oil, substantially as set forth.

In testimony Whereot' We have hereunto set our hands.

llFNltY HERMAN WES'IINGIIOUSE. FRANCE M. lll'lllS.

\Vitnesses:

.l'. hxownnx BELL, R. I]. \VI-u'rTLEsEv. 

